570 CARNIVORA 



margin of the tail, on which account it was referred by Dr. Gray to 

 a distinct genus, with the name of Pteronura sambachi. It should 

 be observed that all Otters have a very distinct inner cusp to the 

 blade of the lower carnassial, but that the relative size of this cusp 

 varies in the different species. 



Extinct Otters. Several species of fossil Otters have been 

 described. Thus in the Indian Siwaliks we have L. palceindica, 

 which is closely allied to L. sumatrana, and a larger form described 

 as L. bathygnathus. The Pliocene of Hessen- Darmstadt yields 

 L. hessica ; while L. diibia, of the Middle Miocene of France, is a 

 species characterised by the small size of the inner cusp of the 

 lower carnassial a character in which it resembles those Tertiary 

 forms described as Trochictis, which are believed to connect Lutra 

 with the Mustelince. Two very large Otters, respectively from the 

 Indian Siwaliks and the Italian Miocene, named L. simlensis and 

 L. campanii, may be regarded either as representing a very distinct 

 Enhydriodont group of Lutra or as referable to a separate genus 

 Enhydriodon. They are characterised by certain peculiarities in 

 the structure of the teeth, and the second upper premolar may be 

 absent in the Indian form. Lastly, the genus Potamotherium con- 

 tains a small Otter (P. valetoni) from the Lower Miocene of the 

 Continent, which differs from all other known Mustdidce in having 

 a minute second upper true molar. This species is evidently a 

 very generalised form approximating to the Viverridce- in its dental 

 formula, and also in the characters of the teeth themselves. The 

 brain, as recently described by Dr. Filhol, differs from that of Lufni 

 and other Mustelines in the great relative width of the anterior 

 extremity of the hemispheres and olfactory lobes, and also in the 

 disposition of the sulci, in both of which respects it more nearly 

 resembles the Viverridce,. 



Latax. 1 Dentition : i f , c i, p f , m 4- ; total 32. Differs 

 from all other existing Carnivora in having but two incisors on 

 each side of the lower jaw, the one corresponding to the first (very 

 small in the true Otters) being constantly absent. Though the 

 molar teeth generally resemble those of Lutra in their proportions, 

 they differ very much in the exceeding roundness and massiveness 

 of their crowns and bluntness of their cusps. Feet webbed. Fore 

 feet small, with five subequal toes, furnished with short compressed 

 claws ; palms naked. Hind feet very large, depressed, and fin- 

 like. The phalanges flattened as in the Seals. The fifth toe the 

 longest and stoutest, the rest gradually diminishing in size to the 

 first, all with moderate claws. Tail moderate, cylindrical, and 

 obtuse ; about one-fourth the length of the head and body. 



1 Gloger, Nova Ada Ac. Cces. Leap. -Car. vol. xiii. pt. 2, p. 511 (1827) : Syn. 

 Enhydra ; Fleming, Philosophy of Zoology, vol. ii. p. 187 (1822). Preoccupied by 

 Enhydris, Merrem, Tent. Syst. Amphib. p. 140 (1820). 



